Boris Johnson clearly admires and relates to Winston Churchill, and with good reason; the two have a good deal in common. Both were talented writers and journalists; both were slightly eccentric members of the Conservative Party; both had a decidedly mixed record while in office; both were viewed by the mainstream as dangerous and erratic opportunists who couldn’t be trusted with too much power; and neither suffered from low self-esteem.
I would imagine that Boris views Brexit as a contemporary version of the Battle of Britain, and wants history to give him credit for delivering it. There are two problems with the analogy, however. First of all, crashing blindly out of the EU without a deal is not the equivalent of saving the UK from the Nazis. Second, Churchill, for all of his many and serious foibles, was unquestionably a great man, while Boris is just a clown.